Stable-surface alloy steel



Patented Jan. '6, 19311 UNITED STATES PATENT OFFICE RALPH 1?, DE VRIES, OF NEWTONVILLE, NEW YORK, ASSIGNOR TOLUDLUM STEEL COMPANY, OF WAT-ERVLIET, NEW YORK, A CORPORATION OF NEW JERSEY STABLE-SURFACE ALLOY STEEL No Drawing.

This invention relates to alloys of steel, and more particularly to such alloys as are known to the trade as stable surface alloy steels.

The main objects of my invention are to provide an alloy steel of new composition which will be resistant to scaling action at high temperatures and which shallhave a fine grain, fair strength, and good ductility It isa-matter of common knowledge that high silicon steels have been employed'for very special electrical purposes, such as transformer sheets, but such alloys when rolled into sheets do not possess any marked degree of strength or easy machining qualities, such as are necessary for most structural and engineering purposes.

I have found that an alloy which includes not only silicon, but also copper and chromium possesses these valuablecharacteristics.

When copper and chromium are alloyed in the steel with silicon, the steel is especially useful for internal combustion engine poppet valves, electrical resistance heating elements, carburizing boxes, and for other purposes wherein metal is desired which will resist scaling particularly at high temperatures. In the course of my experiments, I have found that when this alloy steel is poured the ingots show very large crystals in their structure. Such ingots, however, although apparently having the inherent disadvantages which in the past have been commonly found in all ingots which contain high percentages of silicon, undergo on hammering and rolling, a remarkable transformation. Thebarsformed from such ingots have a remarkably fine Application filed January 20, 1926. Serial No. 82,609.

grain, whether the reducing Work is done furthcrn'iore have good physical properties, from the standpoint of both strength and ductility. From the appearance of fractured ingots, it may be readily seen that copper silicides are formed incident to the melting and freezing of the steel.

The presence of these copper silicides indicates that the silicon is not present in the alloy in the form of a mechanical mixture, but that the silicon is in chemical combination. This either by hammering or by rolling. The bars may account for the fact that the bar rolled from the ingot possessesgood physical properties.

An alloy steel made in accordance with my invention contains chromium from 1.0% to 2%, siliconfrom 1.0% to 6.0%, and copper from 0.5% to 5.0%. I have discovered that Where the minimum of chromium (i. e. 1.0%) is used the permissible minimum. of silicon and copper together is 3.0%, and of this 3.0% at least two-thirds mustbe silicon. All properties given are percentages of the whole by weight.

' Alloys of this composition can be melted practically carbon free, but for some purposes may contain carbon as high as 1%. The usual amount of manganese found in tool and structural steels may be present, or slightly greater amounts up to 1.5% may be used; Impurities and metalloids such as sulphur, phosphorus, etc., will be kept as low as possible. Typical examples of this alloy may be noted as having the following composition:

Chromium Silicon Copper Carbon Iron Per cent Per cent Per cent Per cent 2. 00 4. 00 3. 00 O. 27 Balance 1. 36 4. 00 2. 00 0. 41 Balance Alloy steels made in accordance with my invention can be readily hardened by heating above their critical ranges and then cooling in .Water, oil, or air as desired. For many purposes for which this alloy is adapted,.it will be desirable to.vary.the physical properties by heat treatment which may consist of hardening as mentioned and drawing the steel by reheating'after such hardening,

I claim As a new product, a stable surface alloy comprising chromium about 1%, silicon about 2%, copper about 1%, and carbon less than 1%, the balance being princi ally iron.

In testimony whereof I ave Signed; my name to this specificatioh.

RALPH P. DE VRIES 

